Re: [Postgres-xc-general] Node redundancy

[Josh B. <jo...@ag...>]

On 05/27/2014 07:33 PM, Koichi Suzuki wrote:
> We can reduce the additional latency by performing prepare and commit
> in parallel, I mean, sending command to all the target remote nodes
> first and then receive their response afterwords.
> 
> As I supposed, alternative is to use BDR.   This has very small
> overhead.   We can detect conflicting writes among transactions and if
> each transaction does not conflict, we can apply these writes in
> parallel, not in a single thread as we're doing in streaming
> replication.

Mind you, like BDR itself, we'll still need to figure out how to handle DDL.

> 
> This needs some more work and I think this worth to spend some time.

Yes.  Otherwise we have two unpalatable choices:

- Massive data loss (roll back to barrier) every time we lose a node, or
- Doubling write latency (at least)

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com